1. Field
The present invention pertains generally to communications, and more specifically to a method and apparatus for scheduling transmissions in a communication system.
2. Background
Communication systems, and wireless systems in particular, are designed with the objective of efficient allocation of resources among a variety of users. Wireless systems in particular aim to provide sufficient resources to satisfy the requirements of all subscribers while minimizing costs. Various scheduling algorithms have been developed, each based on a predetermined system criteria.
In a wireless communication system employing a Code Division-Multiple Access, CDMA, scheme, one scheduling method assigns each of the subscriber units all code channels at designated time intervals on a time multiplexed basis. A central communication node, such as a Base Station, BS, implements the unique carrier frequency or channel code associated with the subscriber to enable exclusive communication with the subscriber. TDMA schemes may also be implemented in landline systems using physical contact relay switching or packet switching. A CDMA system may be designed to support one or more standards such as: (1) the xe2x80x9cTIA/EIA/IS-95-B Mobile Station-Base Station Compatibility Standard for Dual-Mode Wideband Spread Spectrum Cellular Systemxe2x80x9d referred to herein as the IS-95 standard; (2) the standard offered by a consortium named xe2x80x9c3rd Generation Partnership Projectxe2x80x9d referred to herein as 3GPP; and embodied in a set of documents including Document Nos. 3G TS 25.211, 3G TS 25.212, 3G TS 25.213, and 3G TS 25.214, 3G TS 25.302, referred to herein as the W-CDMA standard; (3) the standard offered by a consortium named xe2x80x9c3rd Generation Partnership Project 2xe2x80x9d referred to herein as 3GPP2, and TR-45.5 referred to herein as the cdma2000 standard, formerly called IS-2000 MC, or (4) some other wireless standard.
In a communication system, and a wireless system in particular, users are typically assigned to classes, wherein each class has an associated system performance criteria. For example, each class may be treated differently with respect to a fairness criteria, wherein each user in a class is treated similarly. Classes may be treated according to the priority of each class. In one system, users are classified according to services used in the system, such as according to a service plan. Several classes may be present within one communication system.
Accordingly, there is a need for a method and apparatus for scheduling transmissions in a communication system with application to multiple classes of users. Additionally, there is a need for a scheduling method and apparatus that accommodates a variety of different scheduling priorities.
Embodiments disclosed herein address the above stated needs by providing a means for scheduling data transmissions in a wireless communication system. A generalized scheduler allows scheduling of multiple mobile stations, wherein each mobile station may have a different delivery priority parameter. The delivery priority parameter defines the parameter used to affect the desired data transmission delivery rate. For example, a delivery priority parameter may be desired throughput, desired time allotment, desired time delay, etc. The delivery priority parameter values are each mapped to a common scale, referred to as a mapped priority parameter. An operating point is then selected and the corresponding mapped priority parameter values for each mobile user extracted. The generalized scheduler then schedules mobile users using a common mapped priority parameter value. In other words, each user is scheduled to achieve a same proportion within the corresponding delivery priority parameter range.
According to one aspect, in a wireless communication system a scheduling method includes receiving channel condition indicators from a plurality of mobile users, wherein the channel condition indicators correspond to forward link communications, determining a fairness indicator as a function of throughput to the plurality of mobile users, and determining a transmission schedule for the plurality of mobile users, wherein the transmission schedule is a function of the channel condition indicators and fairness indicators.
In another aspect, a program embodied on a computer-readable medium containing computer-executable instructions, includes a first set of instructions for processing channel condition indicators received from a plurality of mobile users, a second set of instructions for determining a fairness indicator as a function of throughput to the plurality of mobile users, and a third set of instructions for determining a transmission schedule for the plurality of users as a function of the channel condition indicators and the fairness indicators.
In still another aspect, a method for transmitting data between one remote station of a plurality of remote stations and a base station in a wireless communication system includes receiving at the base station information transmitted by the one remote station, and adjusting at least one grade of service parameter particular to the one remote station based on the information.
In yet another aspect, a method for scheduling data transmissions in a wireless communication system includes receiving a value for a delivery priority parameter from each of a plurality of mobile users, if any of the delivery priority parameters are different types, mapping each delivery priority parameter to a mapped priority parameter, and determining an operating point based on the mapped priority parameters of the plurality of mobile users.
According to another aspect, an apparatus in a wireless communication system includes a processing element, and a memory storage element coupled to the processing element, the memory storage element adapted for storing computer-readable instructions for implementing: receiving a delivery priority parameter from each of a plurality of mobile user, mapping each delivery priority parameter to a mapped priority parameter, and determining an operating point based on the mapped priority parameters of each the plurality of mobile users.